1. Field of the Invention
The present invention generally relates to a liquid container and an image forming apparatus, and more particularly to an image forming apparatus having a recording head discharging liquid droplets and a liquid container used in the image forming apparatus.
2. Description of the Related Art
As an image forming apparatus such as a printer, a facsimile machine, a copier, a plotter, a multifunction peripheral thereof and the like, there has been known an image forming apparatus using a recording head having a liquid discharge head discharging liquid droplets. In the image forming apparatus, an image is formed by adhering the discharged liquid onto a medium while the medium is fed. Hereinafter, the term “medium” may be called “sheet”. However, the material of the “sheet” is not limited to a specific material. Herein, the term “sheet” is collectively used to refer to any material called a medium to be recorded on, a recording medium, a transfer material, recording paper, recording sheet, and the like. Further, herein, the term “image forming” is collectively used to refer to recording, printing, imaging, typing and the like.
Further, herein, the term “image forming apparatus” refers to an apparatus forming an image by discharging liquid onto a medium including paper, thread, fiber, textile, leather, metal, plastic, glass, wood, ceramic and the like. The term “image forming” refers to not only forming a meaningful image such as characters, figures, and the like on a medium but also forming a meaningless image such as a pattern and the like on a medium (including simply discharging droplets onto a medium). Further, the term “ink” is collectively used to refer to not only any material called “ink” but also any liquid for forming an image, the liquid including a DNA sample, resist, a pattern material, resin and the like. Further, the term “image” is not limited to a planar image. The image includes an image added to a three-dimensional object and an image formed as a three-dimensional model based on a solid model.
As an image forming apparatus (hereinafter may be referred to as an inkjet recording apparatus) as described above, there is a known apparatus. In the known apparatus, a sub tank (a.k.a. ink tank and buffer tank) supplying ink to the recording head is mounted on a carriage, a main ink cartridge (which may also be called a “main tank”) is disposed on the apparatus main body side, and the ink is supplied from the ink cartridge on the apparatus main body side to the sub tank. In another known apparatus, an ink cartridge serving as a liquid container can be replaced along with the recording head.
Japanese Patent Application Publication No. 2007-130979 discloses a sub tank including a container main body (tank main body) defining an ink containing section. The container main body includes an opening section having an opening. A flexible film-like member is joined by means of adhesion or welding to the opening section so that the opening is sealed by the flexible film-like member. In this case, a spring as an elastic member is disposed between the tank main body and the film-like member within the ink containing section so as to bias the film-like member outward. By having the film-like member and the elastic member, a negative pressure generation mechanism is provided.
Japanese Patent Application Publication No. 2009-023251 discloses a tank case having one surface made of a flexible film. A pressure chamber is formed in the tank case, and there is an air chamber communicating with the pressure chamber via an opening section. Further, there is an air-liquid separation film disposed at the opening section, and there is a biasing member biasing the flexible film to the outer direction of the tank case. Further, there is a valve which opens/closes a liquid introducing inlet to introduce the liquid into the pressure chamber based on the movement of the flexible film.
In the liquid container having the container main body (tank case) having the opening section sealed by the film-like flexible member as described above, it may be required for the flexible member to be stably deformed while the liquid is consumed or refilled. On the other hand, there is another demand for reducing the differences in deforming manner depending on the types of liquid filled in the liquid container.